Tooth crown



J. E. RICHMOND TOOTH CROWN.

APPLICATION FILED MAR. 8. 1921.

Emma 001;, 1mm.

Patented Unto W, WEE.

tttttt JOHN EDGAR RICHMOND, OFEUGENJE, OREGON.

TOOTH CROWN.

Application filed March 8, 1921.

To all whom it may concern.

Be it known that 1, JOHN E.RICHMOND, a citizen ofthe United States, residing at Eugene, in the county of Lane and State of Oregomhave invented certain new and useful Improvements in Tooth Crowns, of which the following is a specification.

This invention relates to porcelain tooth crowns as used dentists; and it consists 10 in a crown provi ed with a liner as hereinafter fully described and claimed, and in the method of making and applying the same.

In the drawings, Figure 1 is vertical section through a tooth provided with a crown and liner according to this invention. Fig.

2 is a side view of the tooth, prepared to receive the crown. Fig. 3 is a vertical section through the porcelain crown, and F ig.- 4 is a front view of it. Fig.- 5 is a vertical section through the liner. j

A porcelain crown can be secured on a tooth, according to this invention, without devitalizing the tooth, and without removing its nerve or pulp. The tooth 7, in the jaw of the patient, which requires to be repaired, is prepared as shown in Figs. 1 and 2, by first removing the enamel and as much of the dentine as necessary to form a conical stump 8 without any undercuts. A square shoulder 9 is cut around the neck of the tooth, following the gum line, to form a definite base for the porcelain crown and its liner. The porcelain crowns 10 are made in quantities, and in standard shapes and sizes, of porcelain or other similar material. The chamber 12 in the crown is made conical, with one diameter slightly greater than the other, or

it is otherwise formed, so that the crown will not revolve with relation to the tooth.

The tooth being prepared as hereinbefore described, a porcelain crown is selected of suitable size, shape and color, and having a chamber 12 which will fit very loosely over the stump 8. The base of this crown andthe shoulder 9 on the tooth are fitted together, so that the crown fits smoothly on the shoulder on the tooth and forms a good joint. The porcelain crown is then removed from the stump and the interior of the Serial No. 450,660.

chamber 12 and the surface of the stump are moistened with water, oil, or other lubricant which will prevent wax from adhering to them.

1 The porcelain crown is then warmed, and a small quantity of inla wax is softened by heat and is placed in t e chamber, and the crown is then pressed over the stump. If the crown does not fit'nicely on the stump and its shoulder, it is removed and warmed slightly, so as to soften the wax without melting it, and the crown is again pressed over the stump. When the crown fits nicely on the stump, it is cooled to harden the wax. When the wax is hard enough the porcelain crown is slipped ofl? the wax, andthe wax s5 liner model is in turn removed from the stump, taking care not to distort it. A sprue wire is then attached to the wax model, and the model is invested, burned out, and cast with any suitable metal, in the same way as an ordinary cast gold inlay.

A metal liner 14; is thus formed, which, when the sprue is cut off, and the liner properly finished and polished, will fit smoothly into the chamber of the crown and onto the stump of the tooth. The stump, liner and crown are then secured together by any suitable cement, and the crown will then give approximately the same appearance and service as a natural tooth.

The crowns are made of porcelain, or other material of tooth color, in commercial quantities with the interiors of the crowns ground to definite shapes and sizes so as to make them, within certain limits, interchangeable. The liners, adapters, or bushes are made by the dentists, who do not manufacture the porcelain crowns, but who prepare the teeth, and fit the crowns to them by means of the liners, adapters or bushes as hereinbefore described.

What I claim is: p 1. A porcelain tooth crown provided with a chamber, and a metal liner for the said chamber secured therein and formed of a single piece of cast metal which fits closely in the said chamber and is adapted to fit closely over a tooth stump, said metal liner having been reproduced from a wax model space between the stump and the hollow formed i'nthe space between the selected holcrown, then reproducing the said model in 10 low crown and a stump formed on the tooth metal, and finally cementing the metal liner of the patient above the um line. into the crown and onto the said stump.

5 2. The method of securing a hollow porce- In testimony whereof I have afiixed my ,lain crown to a tooth, which consists in first signature. I

forming a stump on the tooth above its gum line, then forming a wax liner model in the JOHN EDGAR RICHMOND. 

